The 86-year-old said "cyclical" transportation would be needed to get people there and keep them supplied with what they need to survive, but added getting to the planet is still "very realistic".

Dr Aldrin was speaking at the Science Museum in London, where he told people that our focus should shift from the Moon to breaking new ground with travel to Mars.

"I look at where we were 47 years ago leading the world in space exploration, having six landings on the moon, no one has done anything like that ever since ..."

He added: "To take the step, to take the movement, to take the action to begin to occupy... Is there anything bigger that humans could do on Earth than to leave and begin to occupy?"

He said that simply sending people to Mars and then bringing them back would not be as worthwhile as concentrating on making one base self-sufficient.

Something that also needed to be considered, he added, was the mental impact on someone who had decided to spend possibly the rest of their lives on Mars in the colonisation effort.

Dr Aldrin said: "I can see people making that decision. That's the most important thing...But I can also see things getting a little tough and they regret the decision and their functioning going down and that being disruptive to people."